The rapid proliferation of local area network (LANs) in the corporate environment and the increased demand for time-sensitive delivery of messages and data between users has spurred development of high-speed (gigabit) Ethernet LANs. The 100BASE-TX Ethernet LANs using category-5 (CAT-5) copper wire and the 1000BASE-T Ethernet LANs capable of one gigabit per second (1 Gbps) data rates over CAT-5 data grade wire use new techniques for the transfer of high-speed data symbols.
Conventional 1000BASE-T Ethernet LAN drivers, in addition to nearly all other signal processing/communication chips and systems, use band-gap reference circuits. These band-gap reference circuits are able to generate relatively constant reference voltages that have a well-defined magnitude, as well as minimal process variation, temperature variation, and voltage variation.
However, conventional CMOS-based band-gap reference circuits are highly prone to variations as a result of random mismatches of the MOS transistors. These mismatches are often manifested as current mismatches and, in the case of operational amplifiers, as offset voltages.